TDI Smoking: Causes and Solutions

Hi, I have an Audi A3 with engine code AGR, 66kW/90hp, and a tuning chip. It has 135,000 km on the odometer.
Okay, so I'm having a problem where it's sputtering under full load. I've already tried disabling the EGR system as a test, disconnecting the vacuum hose, and sealing it off from the exhaust side. Before, the speedometer only showed a top speed of 185 km/h. After messing with the EGR system, it's running much better, around 205 km/h, and the sputtering isn't as bad anymore.
It only produces a large cloud of smoke when I release the accelerator and then press it down again.
'Oh, and I just remembered, I had a friend with a diagnostic tool check the mass airflow sensor (MAF), and it's okay. However, the boost pressure didn't go above 0.78 bar! This was also before I disabled the EGR valve!'
Okay, and now I don't know what to do!!
I've also had the chip installed for a while now, and after the installation, it didn't cause any problems.

Hi.

For a tuned 90s engine, a boost pressure of 0.78 bar is definitely too low.

Normally, I would now say: Check/replace the turbocharger wastegate solenoid valve, inspect the hoses around it, and if necessary, investigate the turbocharger itself (wastegate or variable geometry turbine?).

However, since things can also go wrong with chip tuning , the 0.78 bar might also be just a programming error, so that one would be looking for the problem in the hardware . . .

Hi.

I went to the chip tuner today and had the software checked again. He said it was okay. He also made new chips for me, but it didn't make any difference.

The top speed is approximately the same as the stock version. It has been tested with a Golf 3 TDI with known 90 horsepower.

The boost pressure is still 0.78 bar. What is the purpose of the boost pressure control valve, and how does it work exactly? Should I replace it next?

I still have a turbocharger without variable geometry.

The hoses seem to be fine, as far as I can tell!

Is it possible to install a different turbocharger? For example, one from a common rail engine? Would it work with a naturally aspirated intake manifold and exhaust manifold, or does it not work due to the connections? What about the engine's durability?

altibe wrote:

The boost pressure is still 0.78 bar, what is the purpose of the boost pressure control valve, or how does it work exactly? Should I replace it next?

Hi.

Okay, let's try that. It's the option that costs the least initially.

Quote:

Is it actually possible to install a different turbocharger? For example, one from a common rail engine? With an intake manifold and exhaust manifold, or does it not work due to the connections? What about the engine's durability?

No, PD chargers are VTG types, and your engine control unit won't be able to handle them – even if you were to modify the mechanics to make them compatible.

Hi,

Since my TDI Leon with 110 hp and ASV engine is also producing excessive smoke, I checked the turbocharger pressure control valve.
Checked the valve according to ULF's instructions.

ulf once provided the following instructions for checking the turbocharger boost control valve:
written:

Remove the valve and hold it with the hose connections facing downwards. Apply suction to the OUT connection with your mouth; air should flow in. Then, block the ATM inlet --> the valve should be airtight.



I can confirm that.

Then apply pressure to the valve and use the VAC connection to create suction: air must flow in. Turn off the power --> the valve must seal quickly and completely.



Whether with or without tension, you can always suck in air.


Turn the power back on, vacuum, and hold the OUT connection --> Valve is sealed.



Whether with or without pressure, the valve is almost completely sealed.
The only thing that happens with my valve when voltage is applied is...
The change is that the ATM connection is either closed or opened.
The part number for my valve is 1J0 906 627 A.
It would be great if someone (ideally ulf) could take the time to look at this again.
The instructions might be helpful to check. Otherwise, my valve would need...
Yes, it's completely broken.

Achim wrote:

Quote: Remove the valve and hold it with the hose connections facing downwards. Apply suction to the OUT connection with your mouth; air should flow in. Then, block the ATM inlet --> the valve should be airtight. I can confirm that to that extent. Quote: Then apply pressure to the valve and use the VAC connection to create suction: air must flow in. Turn off the power --> the valve must seal quickly and completely. Whether with or without tension, you can always suck in air. Quote: Turn the power back on, vacuum, and hold the OUT connection --> Valve is sealed. Whether with or without pressure, the valve is almost completely sealed. The only thing that happens with my valve when voltage is applied is... The change is that the ATM connection either closes or opens. The part number for my valve is 1J0 906 627 A. It would be great if someone (ideally ulf) could take the time to look at this again. The instructions might be helpful to check. Otherwise, my valve would need... yes, it is completely broken.

Hi.

According to your description, your valve is actually behaving "as if it's broken."
I don't have the part number handy right now, I'll check again.
However, I can't imagine that your valve is working properly. Unless, perhaps, your valve is installed in the opposite direction compared to mine.
Are the hose connections located on the bottom or the top?

Hi,

That happened really fast.

'On my device, the valve with the hose connections and the gray cap is located...'
attached at the top.
I forgot something: make sure to let the air pass through the OUT port.
This step is quite strenuous.

Achim wrote:

In my case, the valve with the hose connections, which has a gray cap, is mounted facing upwards. I forgot something: make sure to let the air pass through the OUT port. This step is quite strenuous.

Hi.

Mine is installed with the hoses facing downwards.

"During the test, please keep the valve in its installed position; that's definitely the correct way. This might help to "normalize" its behavior, including the tight fit in the first step."

Hi,

Okay, I'll try that. But not until after a week of vacation.
The mounting position should not change when the voltage is applied to the function.
Therefore, the valve would be faulty or malfunctioning, wouldn't it?

Achim wrote:

The mounting position should not change when the voltage is applied to the function. Therefore, the valve would be defective or??

Hi.

It doesn't have to be that way. Mine behaves as if it were defective when tested for suction, but it isn't.

Hi,

Let's try a different approach.
If the charge pressure control valve (is there no abbreviation for it?) is defective,
It's possible to check the actual boost pressure during a test drive, for example, using a tool like VAG-COM.
Is it not reaching the target boost pressure, or am I wrong again?

Achim wrote:

If the charge pressure control valve (is there no abbreviation for it?) is defective, It's likely that during a measurement run, for example, using VCDS (formerly VAG-COM), the actual boost pressure would be displayed. will not reach the target boost pressure, or am I wrong again??

Hi.

Yes, that's correct. If the actual boost pressure and the actual duty cycle for the valve are within their respective target ranges, then the boost pressure control loop is functioning correctly.
At least during the measurement run...

Have you solved the problem yet?
I'm interested, I'm having similar problems!

Regards,
Sneezy.

Well... I'm sure that would interest many people here, including me.
Apparently, altibe is no longer interested in finding a solution to the problem.
It's always a shame to see dedicated people wasting their time with such clueless individuals. A little feedback would be appreciated.
Before they start flooding this forum with questions, they should just go to the workshop and pay for the service .

"Poster altibe," for example, hasn't actually helped anyone here, but has only wasted other people's time with their rambling.

Best regards, Rainer.